Form constructor to test the #required property without #title.
function form_test_validate_required_form_no_title($form, &$form_state) {
$form['textfield'] = array(
'#type' => 'textfield',
'#required' => TRUE,
);
$form['actions'] = array(
'#type' => 'actions',
);
$form['actions']['submit'] = array(
'#type' => 'submit',
'#value' => 'Submit',
);
return $form;
}